Field of the Invention
This invention relates to a marine steering gear, and more specifically to a gear comprising both main and emergency steering means.
Conventional steering engines comprising actuators of the two-ram-four-cylinder type that include two or more power units (each composed of a hydraulic pump, a motor for driving the pump, etc.), the one-ram-two-cylinder type, or the rotary vane type are all devoid of hydraulic-pressure-replenishing means for emergency use. When any of the hydraulic pipe lines connected to the actuator, couplings, actuator packings, or the like has been seriously damaged, leakage of the hydraulic fluid or oil from the particular line or actuator will consequently take place. A delay in finding out or taking a proper step against the damage can lead to complete inability of steering the ship, with the oil tank of the power unit emptied.
To make matters worse, such a failure in the hydraulic system is likely to occur in heavy weather. When it happens, the rudder blade that is swamped by frantic waves is no longer hydraulically locked by the actuator, because of the loss of oil in the steering engine, but is beyond control at the mercy of the waves. Making a repair to the damage or recovering in such situation involves great danger. A lag in the recovery can result in a grave trouble that will decide the fate of the vessel.